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Betta foerschi

Betta foerschi
Foersch's Betta
This species lends its name to the foerschi group/complex of closely-related Betta species. At time of writing this assemblage also includes B. mandor , B. rubra and B. strohi. Members of the group are widely-regarded as being more closely related to the bubblenesting Bettas than other mouthbrooding congeners due to various morphological similarities, particularly in the structure of head and mouth as well as general colouration. There are also some differences in spawning behaviour compared with other mouthbrooding Bettas (see section above) that would seem to reinforce such suspicions. 

Many of the fish sold in the trade as Betta foerschi turn out to be B. mandor , which was described as a separate species by Tan and Ng in 2006. We've also seen the latter being sold as Betta foerschi "ninja". These two can be very tricky to tell apart and so far the only information we´ve been able to collect is the following: Betta foerschi possesses less transverse scales than B. mandor (8.5 vs. 9.5-10); less lateral scales than B. mandor (28.5-31 vs. 32-34); shorter caudal fin than B. mandor (127.2-133.5 % SL vs. 136.7-149.1); larger caudal peduncle depth than B. mandor (17.5-21.0 % SL vs. 15.9-18.3); larger body depth at dorsal-fin origin than B. mandor (24.4-28.9 % SL vs. 21.2-24.2); shorter dorsal-fin base than B. mandor (10.0-12.2 % SL vs. 12.3-16.7); larger interorbital distance than B. mandor (9.6-13.4 % SL vs. 8.4-9.5); larger snout length than B. mandor (7.3-8.0 % SL vs. 3.9-7.0). 

Foerschi and Mandor have red opercular bars, Strohi have gold bars.